1. Field of the Invention
The present invention relates to a connection unit provided between an optical amplifier and optical cable, an optical fiber line unit accommodated in an optical cable, an optical cable, and an optical transmission system including an optical cable and optical amplifier.
2. Related Background Art
In a submarine optical cable or the like, to transmit optical signals over a long distance, repeaters are provided at predetermined distance intervals (about 90 km at maximum; about 50 km in general) to amplify a weakened optical signal.
An optical cable has a plurality of optical fiber lines in an optical cable sheath portion, and the plurality of optical fiber lines are respectively connected to a plurality of optical fibers extending from an optical amplifier (to be also referred to as an optical amp hereinafter) mounted in each repeater. A plurality of optical signals propagating through the plurality of optical fiber lines collectively strike the optical amp via the plurality of optical fibers extending from the optical amp to be collectively amplified.